There
is no portable FORTRAN 77 syntax for using MPI_Alloc_mem. There is no portable
Fortran syntax for using pointers returned from MPI_Alloc_mem. However,
MPI_Alloc_mem can be used with Sun Fortran compilers.

From FORTRAN 77,
you can use the following non-standard declarations for the SIZE and BASEPTR
arguments:

INCLUDE "mpif.h"
INTEGER*MPI_ADDRESS_KIND SIZE, BASEPTR

From either FORTRAN 77 or Fortran 90, you can use "Cray pointers" for
the BASEPTR argument. Cray pointers are described further in the Fortran
User’s Guide and are supported by many Fortran compilers. For example,

Almost all MPI routines return an error value; C routines as the
value of the function and Fortran routines in the last argument. C++ functions
do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS,
then on error the C++ exception mechanism will be used to throw an MPI:Exception
object.

Before the error value is returned, the current MPI error handler
is called. By default, this error handler aborts the MPI job, except for
I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler;
the predefined error handler MPI_ERRORS_RETURN may be used to cause error
values to be returned. Note that MPI does not guarantee that an MPI program
can continue past an error.